Many conventional motor vehicles, such as the modern-day automobile, include an air dam that is engineered to improve the aerodynamic characteristics of the vehicle body. A traditional air dam, which is sometimes referred to as an “air deflector”, is mounted on the underside of the front-end structure of the vehicle body, extending downward into proximity with the roadway. Air dams improve the handling and control of the motor vehicle, increase fuel economy, and also improve the routing of air flow for cooling/heat exchange in the vehicle powertrain and air conditioning systems by managing the flow of turbulent air under and around the vehicle chassis and affecting internal airflows.
An air dam that is fixedly suspended from underneath the front-end structure of the vehicle may be damaged upon impact with a curb, driveway incline, or other roadway obstruction. Many air dams are fabricated from molded plastic or fiber-reinforced polymer, which can yield to some extent upon contact with an obstruction. However, vehicle styling considerations may dictate that the air dam have a curved shape when viewed in the plan view. Such curved configurations inherently stiffen the air dam, which in turn limits the extent to which the air dam can yield when striking a curb or other obstruction.
To minimize or eliminate damage to the air dam, some prior art approaches propose movably mounting the air dam beneath the front-end structure of the vehicle body. Prior art retractable air dams typically translate linearly from a stowed position, in which the air dam is raised above the road surface and stored in an internal cavity, and a deployed position, in which the air dam is lowered into proximity with the roadway. At lower speeds when the air dam is relatively ineffective, the air dam remains in the stowed position so as to eliminate inadvertent contact with roadway obstructions. At higher speeds where roadways tend to maintain negligible gradients and have no obstructions, the air dam is lowered to reduce aerodynamic drag.